Chapter 19 Eukaryotic Genome Organization and Control
The Packing of Eukaryotic DNA:
Levels of Control of Protein Synthesis in Eukaryotes:
Acetylation of histones loosens chromatin:
DNA Sequences Upstream of a gene control its Transcription:
How Enhancers Influence Transcription:
Differential Transcription leads to Differentiation:
Alternative Splicing can make multiple polypeptides from one gene:
mRNA degradation: If mRNA cannot be translated, no protein can be made:
Mutations can cause proto-oncogenes to become oncogenes:
Ras and p53 mutations cause many cancers:
Colon Cancer Illustrates the multi-step nature of cancer:
The Human Genome by the Numbers:
Barbara McClintock and Eukaryotic Transposons:
Evolution in Gene Families
Multi Gene Families contribute to evolution.
Chapter 19- Key Points
Students may find the large number of control points regulating eukaryotic gene expression
bewildering. It is important to rem remember the significance of these mechanisms in allowing
exquisite control of gene expression during development and in changing environments.
The significance of the large number of transposable elements in eukaryotic genomes and the
contribution of these elements to the evolution of eukaryotic genomes are difficult concepts for
students to master.
• Two features of eukaryotic genomes present a major information-processing challenge.
° First, the typical multicellular eukaryotic genome is much larger than that of a prokaryotic cell.
° Second, cell specialization limits the expression of many genes to specific cells.
• The estimated 25,000 genes in the human genome include an enormous amount of DNA that does not
code for RNA or protein.
• This DNA is elaborately organized.